1. Field of the Invention
The invention relates in general to an adjusting circuit and an adjusting method and in particular to an image adjusting circuit and an image adjusting method.
2. Description of Related Art
In recent years, computation power of computers increases at a rapid pace, and digital media have become one of the major instruments for demonstrating creativity and imagination. With advancement of digital image processing and imaging products, images of various types can be recorded and stored in digital format. There are a number of different digital imaging products including thin film transistor liquid crystal displays (TFT-LCD), digital still cameras, digital video camcorders, digital televisions, and so forth. The quality of ultimately output images relies on the front-end image-capturing devices, the digital image processors, the back-end digital image output devices, etc.
After an image has been digitally processed, the image is output from the back-end equipment of a digital imaging apparatus in form of an image or a document. According to digital image processing (DIP) principles, analog images are “digitized” before the two-dimensional or the three-dimensional images are processed by computers. The method includes “sampling” an image on all locations and then analyzing and recording the brightness, the color, and the location of each point of the image. Each sampling point of the image is referred to as a pixel, and a set of pixels together forms the image. The image data related to each pixel include its gray scale value, color, and brightness, and the image data are stored as data arrays into computers for further processing. The image data are then digitally processed and transmitted to an image output device in form of digital image signals.
After the image output device receives the digital image signals, the image data are up-sampled. If a low order filter is adopted in the image output device to up-sample the image data, data at high frequency in the digital image signals are blurred. By contrast, when a high order filter is utilized for up-sampling the image data, the data at high frequency in the digital image signals can be retained. However, with use of the high order filter for up-sampling the image data, unacceptable visual effects such as light contour are apt to be generated at sharp edges of the image, and ripples are likely to be formed due to ringing effects or ripple effects. As such, the quality of the ultimately output images is deteriorated.